Variable electric condenser



F. R. MACHIN VARIABLE ELECTRIC CONDENSER Filed Nov. 7. 1925 2 Sheets-Sheet l Se t. 13, 1927.

R. MACHIN VARIABLE ELECTRIC CONDENSER Filed Nov. '7, 1925 2 Sheets-Sheet 2 Patented Sept. 13, 1927.

PATENT OFFICE.

FRANK nown'rnnn MAOHIN, or LONDON, ENGLAND.

VARIABLE ELECTRIC CONDENSER.

Application, filed November 7, 1925, Serial No. 67,543, and in Great Britain August 26, 1925.

This invention relates to operating mechanism for variable electric condensers, moving coil holders, variometers and like tuning and adjusting devices for radio receiving or other apparatus in which the position of a movable member hasv to be finely adjusted.

The principal object of the invention is to provideoperating mechanism, having a rotary operating member which can be rotated directly by hand for relativelycoarse adjustment and can also be rotated through speed reduction gear for relatively fine adjustment.

A further object of the invention is to provide operating mechanism capable of being applied to existing condensers to enable a Vernier or fine adjustment to be obtained without the necessity for providing an independently movable Vernier condenser plate.

'Further objects of the invention are to provide operating mechanism for variable electric condensers and other tuning and adjusting devices having Vernier adjustment which is simple and compact and which is free from backlash and other evils which usually attend the useof reduction gearing.

Preferred embodiments 'of the invention are illustrated in the accompanying drawings in Which:

Figure 1 is an elevation partly in section of a variable condenser provided with operating mechanism constructed according to one form of the invention. 1

Figure 2 is a section on the line -22 of Figure 1.

Figure. 3 is a view similar toFigure 1 4 of a condenser provided with operating mechanism constructed according-to another form of the invention, and,

' Figure 4 is a cross section through operating mechanism similar to that shown in Figures 1, 2 and 3, provided with additional reduction gearing for use when exception-v ally fine adjustment is required.

Referring first to Figures. 1 and 2, the condenser 1 isof a wellknown type comprising fixed plates 2 and movable plates 8 mounted on a rotary spindle 4 which projects through a holein' a panel 5,- to which the condenser 1- is secured in any usual or preferred manner.

'- The end of the spindle't which projects through the panel, carries an operating handle 6 which is not fixed to the spindle handle 6, which is held in position by being screwed to a dial 8 engaging over a reduced cylindrical portion 9 of the member 7 and abutting a shoulder 10 formed on the latter.

The rotary operating member 7 consists of a hollow cylinder, open at its upper end and formed with a pair of helical slots 11 which are engaged by pins or bars 12, which extend through the slots 11 and engage at their outer ends in longitudinal grooves 13 formed in the inner walls of thehandle 6.

The inner ends of the pins 12 are secured to a nut 14 screwed on a rotary spindle 15 which projects through a bearing aperture in the upper wall of the handle 6 and carries an operating handle or knob 16 of smaller diameter than the handle 6.

The dial 8 is held frictionally in adjusted position by means of a spring 17 which in the example shown is clampedagainst the panel 5 by means of the usual fixing 'bllSh '18 which clamps the condenser to the panel.

The operation is as follows For coarse adjustment of the condenser. the handle 6 is rotated directly by hand and the operating member 7 rotates with the handle by reason of this fact that these members are connected together by the pins 12. a

When it is desired to efiect'a fine adjustment, the knob1 6 is rotated so that the spindle 15 is rotated in the nut 14 with the result that the latter is traversed along the spindle. As the ends of the pins 12 are guided in the grooves 13 in the handle 6,

the axial movement of these pins causes the operating member 7 to be partially rotated in the handle 6 with the result that the spindle 4 of. the condenser is rotated, the handle'6 being held against rotation by'the action of the spring 17.

The rotary move- I ment of the member 7 is, however, much 7 slower than that of the knob 16 and this enables very fine adjustment of the positions ofthe plates 3-to be effected.

The construction shown in Figure 3 is exactly similar to that shown in Figures 1 and 2 except for the fact that the spindle of the condenser is plain instead of being screwed and is frictionally gripped in a bore in the member 7 whilst the spring 17 is clamped to the dial 8 by a collar lived to the part 9 ot the member 7. i

In the construction shown in Figure l, the operating; handle 6 which is mounted on an operating member (not shown) in the same way as the handle Ci shown in Figures 1 and ii. is jiirovided with an additional. speed reduction device comprising an ebonite sleeve if) disposed in a groove or recess in the wall at the handle 6 and pivoted to the wall by means of a pin 20. The sleeve 19 carries a spindle 21 provided with a handle 92 and :lformed with a worm meshing with a. worm wheel 2i which is disposed between the member T and the upper wall oi? the handle (3 and is secured to the spindle The spindle in is provided with an operating lUiUlJ (not shown) similar to the lanob 16 shown in Figures 1 to S and operates in the same manner as the sj' indle shown in Figures 1 to 3. The sleeve 19 is normally rocked in a clockwise direction from the position shown in Figure rt so that; the worm 2?) disengaged from the worm wheel 5351: thus allowing the spindle 15 to be rotated directly by means of its operating; knob. When exceptionally fine adjustment of the movable condenser plates is desired however, the sleeve 19 is moved into the position shown in Figure et in which the worm 23 meshes with the worm wheel 2d and the shaft is then rotated through the worm wheel by rotating the handle 22.

In order to facilitate accurate adjustment, the operating member 7 may carry a pointer 25 ,(l igures 1 to 3) which projects through an opening in the cylindrical wall oil the handle 6 and moves over gradnations 26 on the dial 8. When the additional speed re duction device shown in Figure at is used the flange 27 ot' the'handle may carry gradnations which are read against a mark on the tlangge 28 of the sleeve 19.

Any of the operating}: devices described above can readily be applied to existing condensers or other tuning or adjusting devices by screwing or otherwise securing the rotary operating member 7 to the operating spindle of the condenser or other device. In on dcr to enable the knob 16 to be rotated without disturbing the handle ti, it is necessary to provide a. frictional braking device capable of holding the handle (3 when the ltnob 16 is rotated. This may be done in either of the ways shown in Figures 1 to 3 or in any other convenient manner.

1. Operating mechanism for variable electric condensers and other adjusting de vices comprising; a rotary operating member. a hand actuated member rotatable on said operating member, cam surfaces on said operating, and hand actuated members, a sliding member co-operating with said tam surfaces to cause relative rotation between said operating andhand actuated members, yielding meansi or holding said hand actuated member in adjusted position, and a second hand actuated member for operating said sliding member.

Upcratii'ig mechanism for variable electric ccmdcnsers and other adjusting dcvices, comprising a rotary operating member, a handle rotatably mounted on said operating: member, a. recess in said ope ating member, a second handle rotatably mounted on said first mentioned handle, a screw spindle lived to said second handle and projecting into said recess. a nut on said spindle, slots in said operating member, grooves in said handle, said slots and grooves forming, two sets of guide surii'aces, audpins on said nut projecting throrurl'i s id slots and enco ing said grooves, at least one at said sets guide surfaces being inclined to the axis oi? the operating member.

3. Operating mechanism for variable electric condensers and. other adjusting de vices coinprising,- a rotary operating meinher, a handle rotatabl mounted on said operating member, a second handle rotat' abl mounted on said lirstanentioned handlc, cam mechanism actuated. by said second handle for rotating said operating member relatively to said first mentioned handle, a third handle rotatably mounted on saidllirst mentioned handle and. speed reduction mechanism for driving said second handle from said third handle.

l. Operating mechanism for *ariable electric condensers and. other adjusting de vices according to claim 3 wherein said speed reduction mechanism is declutehable.

5. Operating mechanism for variable electric condensers and. other adj listing dcviccs compri ingr a rotary operating member, a handle rotatably mounted on said operating member, said ojjieratingr member being disposed within said handle. a second han dle rotatably mounted on said first mentioned handle and having; a. spindle projecting); into said first mentioned handle, -am mechanism actuated by said second handle for rotating}: said operating member relatively to said first mentioned handle, a worm wheel on said spindle within said first meir tioned handle a worm meshing with said worm wheel and having a spindle projecting from. said first mentioned handle and a. third handle mounted on said worm spindle.

G. Operating mechanism for variable electric condensers and other adjusting devices according to claim 5 including a sleeve mounted pivotally on said first mentioned handle, said worm spindle being j ournalled in said sleeve.

7. 0pc rating mechanism for variable electric condensers and other adjusting de vices comprising a hollow cylindrical rotary operating member, a hollow cylindrical handle and projecting from the same, asec 0nd handle mounted on said spindle, slots in said operating member, grooves in said first mentioned handle, a nut on said spindle and pins on said nut projecting through said slots and engaging in said grooves, said pins 10 co-operating With said slots and grooves for rotating said operating member in said first mentioned handle.

In Witness whereofI affix my signature.

FRANK ROWNTREE MACHIN. 

